Wall outlet and switch box hole cutter

ABSTRACT

A cutter accessory adapted to be used with portable power tools for cutting holes in sheet material such as wallboard and panelling. The device includes a housing; an endless chain disposed in the housing for rotation therein, and a plurality of cutting edges carried by the chain and extending forwardly from the housing. A drive member located in the housing is adapted for coupling to a rotary power source such as a drill for driving the chain. Improvements are described which permit the hole to have any desired shape (e.g., rectangular), to be stable against motion in the plane of the workpiece and to facilitate centering of the cutter on a desired location.

United States Patent [191 Chailer Sept. 3, 1974 1 WALL OUTLET AND SWITCH BOX HOLE CUTTER [76] Inventor: John D. Chailer, 2115 Weatherbee,

Fort Worth, Tex. 16110 [22] Filed: Sept. 25, 1972 [21] Appl. No.: 291,726

Related U.S. Application Data [63] Continuation-impart of Ser. No. 258,081, Aug. 23,

1972, abandoned.

[52] U.S. Cl 408/22, 408/48, 408/117, 144/73, 144/144 [511 InLCl B2 3b 51/06, 1323b 41/04 [58] Field ofSearch 408/22,48, 117; 144/144 [56] References Cited UNITED STATES PATENTS 1,667,347 4/1928 Field 144/73 2,536,650 l/l95l Martinez.... 144/144 R 3,499,353 3/1970 Ewell 408/22 X Primary Examiner-Francis S. Husar Attorney, Agent, or Firm-Edward D. Murphy; Leonard Bloom; Joseph R. Slotnik [57] ABSTRACT A cutter accessory adapted to be used with portable power tools for cutting holes in sheet material such as wallboard and panelling. The device includes a housing; an endless chain disposed in the housing for rotation therein, and a plurality of cutting edges carried by the chain and extending forwardly from the housing. A drive member located in the housing is adapted for coupling to a rotary power source such as a drill for driving the chain. Improvements are described which permit the hole to have any desired shape (e.g., rectangular), to be stable against motion in the plane of the workpiece and to facilitate centering of the cutter on a desired location.

2 Claims, 5 Drawing Figures WALL OUTLET AND SWITCH BOX HOLE CUTTER RELATED APPLICATION This application is a continuation in part of my copending application, Ser. No. 258,081, filed Aug. 23, 1972, entitled Wall Outlet and Switch Box Hole Cutter and now abandoned.

This invention relates to hole cutters and is specifically directed to a device for cutting rectangular openings in panels or walls.

In the construction and remodeling of houses and buildings, it is frequently necessary to cut through an installed wall of plaster, plasterboard or panelling to mount an outlet or switch box or to make use of a previously installed box. At the present time, this requires locating the place where the box is or is to be mounted, then measuring carefully to mark a level, rectangular outline on the wall, and cutting to the outline. The cutting is also time-consuming as the operator must observe and follow the course of the outline rather carefully so as to remove all of the rectangular section without cutting into the adjacent wall. The purpose of this invention is the provision of an improved cutting device which simplifies this task and which makes it possible for the operator to locate and cut the desired opening much more quickly and easily than has previously been feasible.

It is accordingly an object of this invention to provide a new and improved cutter for producing rectangular holes.

Another object of this invention is the provision of a new and improved hole cutting accessory for power tools.

It is also an object of this invention to provide an improved hole cutter having provision for accurate centering and also for good lateral stability.

Further objects and advantages of this invention will become apparent as the description and illustration thereof proceed.

Briefly, in accord with one embodiment of this invention, a shaped hole cutter is provided which includes at least one drive shaft disposed along the periphery of the shape and adapted to be engaged with a power source such as a portable electric drill. Drive means such as a toothed wheel is provided to couple the shaft to a moving cutter, and idlers are positioned to guide the cutter along the desired shape. To prevent twisting during use, at least two points within the periphery are provided with drill points which enter the work prior to engagement of the cutter with the work. In a preferred embodiment, the shape to be cut is rectangular and a sight hole is provided in the center of the rectangle for positioning the cutter at a predetermined location. I

In the drawings:

FIG. 1 is a perspective view illustrating a device in accord with the present invention in a specific use;

FIG. 2A is a side elevation illustrating the initial entry of the device of FIG. 1 into a wall section;

FIG. 2B is a side elevation similar to that of FIG. 2A, but illustrating a later stage in the operation of the device;-

FIG. 3 is a front elevation of the device of FIG. 1 with a portion of the cover broken away; and

FIG. 4 is a cross sectional view taken along the lines 4-4 of FIG. 3.

LII

FIG. 1 illustrates one application of the preferred embodiment of this invention. In this illustration, a newly installed wall It), typically of plasterboard or panelling, has been put in place over a previously installed junction box 11 which is to receive an electrical wall outlet. The junction box is, of course, placed at a known location so that its position behind the wall 10 can readily be determined and marked, for example with a penciled X 12 at its center. The installer of the outlet must next cut an opening in the wall at the position of the junction box so that the outlet can be connected and mounted and the opening covered with a suitable cover plate. The device of the present invention simplifies and speeds this operation.

The installer simply makes use of an electric drill 13 connected to a wall cutter 14 in accord with this invention which is shaped and sized to correspond to the opening required for the junction box. The drill is connected via its chuck 15 to one of two drive shafts 16, the device is centered over the junction box by means of a sight hole 17 and the penciled X, and the device is operated by turning on the drill to cut the opening in one, simple operation. The installer may then proceed to place the outlet and cover plate. A handle 18 may be provided on the cutter if desired.

As is shown more clearly in FIG. 2A, the cutter 14 includes a pair of drill points 20, which preferably are extensions of the drive shafts l6, and a series of cutting teeth 21 which extend around the periphery of the cutter 14. The drill points 20 are longer than the teeth 21 so that the points may be engaged with the wall l0 and started before the teeth engage. This provides for a degree of self-feeding action as the drill points act to draw the cutter into the wall, but more importantly, the use of two points stabilizes the cuter against twisting which might otherwise occur as the cutting teeth engage the wall.

FIG. 2B shows the cutter at a later point in its operation. As the drill points break through the wall, the teeth have cut a path on the desired outline and there is no further danger of twisting. Continued operation of the cutter separates the severed wall portion from the wall 10 and it is removed with the cutter.

FIG. 3 shows a front elevation of the cutter 14 with a portion broken away to illustrate the internal construction. The cutter includes a housing member 25 which encloses a track 26 for a chain 27 on which the cutting teeth 21 are carried. The four corners of the rectangular shape are defined by sprockets, two of which, 28 and 29, are mounted on the shafts 16 to form alternative drive means while the other two, 30 and 31, are idlers on short shafts 32 mounted in the housing 25. Thrust washers 33 may be provided for each of the sprockets and a cover plate 34, held in place by bolts 35, completes the assembly. The cover plate may also include an internal flange 36 which defines an inner boundary of the track 26.

FIG. 4 is a cross sectional view which illustrates the manner in which the drive sprocket 29 and idler sprocket 30 are mounted in the housing 25. Sleeve bearings 37 are preferably provided to receive the shafts 16 and 32.

In accord with the present invention, the specific shape followed by the chain, and thus cut by the teeth, is defined by the combination of drive means and idler means, specifically the sprockets 28-31. In the particular embodiment shown, the desired shape is that of the typical junction box for outlets and switches. However, it is noted that other shapes and arrangements of sprockets, both drive and idlers, may easily be devised to meet the needs of particular instances. For example, the installation of such items as central vacuum cleaners, overhead lighting fixtures, telephones and multiple switch locations could all be benefitted by devices in accord with this invention. Suitable tools specific to particular applications could be produced, as in the illustrated embodiment, or an adjustable device might be made to accommodate a variety of shapes. In either case, a key aspect of this invention is the use of idler means to shape the cutter to the desired path.

Another important aspect of this invention is the provision of a plurality of drill points which enter the work ahead of the cutting teeth. Since the cutting elements are operating in one direction, they may produce sufficient torque, when they engage the work, to twist the cutter and damage the adjacent surface. The use of at least two drill points longer than the teeth prevents this and causes the cutter to enter the work at the desired position. The provision of drive shafts on both of the sprockets having drill points is not necessary, but it does provide added convenience for situations where one side of the cutter may be too close to an obstruction to permit use of the drill.

Another notable feature of this invention is the provision of the sight hole 17. This hole, which can be provided in this device because the peripherally mounted drive is off-set, enables the opening to be cut as soon as the center is located without need to measure or mark the outline of the box. This permits a significant reduction in the amount of time spent in making the opening.

It will of course be appreciated that, while certain specific embodiments have been described and illustrated, many changes and modifications will occur to those skilled in the art which do not depart from the essence of this invention. For example, one such modification is the substitution of a band saw-type blade or other cutting element with suitable modification of the internal drive and idler means. Accordingly, it is intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A cutting device adapted for use with a source of rotary power for cutting rectangular openings in sheet material comprising a housing; an endless driven member mounted for movement within said housing, said member having cutting means extending forwardly from said housing, said member and said cutting means being arranged in a rectangular shape corresponding to said opening; drive means located within said housing at one corner of said opening for driving said member; a plurality of drill points extending forwardly from said housing, said drill points being longer than said cutting means to enter a workpiece ahead of said cutting means whereby said device is stabilized against movement in the plane of the workpiece; said housing including an aperture located in the center thereof to enable an operator to sight on the center of a desired hole location.

2. A cutter accessory adapted to be used with a portable drill for cutting rectangular holes in sheet material comprising a housing; an endless chain mounted for movement within said housing; a plurality of cutting blades carried by said chain and extending forwardly of said housing; drive means for driving said chain within said housing, said drive means including first and second independent drive means offset from the center of said rectangles, each of said first and second drive means including a drill point extending forwardly of said housing, said drill points extending further from said housing than said blades to define the location of said cutter prior to engagement of said blades with the work whereby rotational instability is reduced; a plurality of idlers juxtaposed with said drive means to lead said chain around the corners of a desired rectangular shape; and said housing including an aperture extending therethrough for sighting on the center of a location to be cut. 

1. A cutting device adapted for use with a source of rotary power for cutting rectangular openings in sheet material comprising a housing; an endless driven member mounted for movement within said housing, said member having cutting means extending forwardly from said housing, said member and said cutting means being arranged in a rectangular shape corresponding to said opening; drive means located within said housing at one corner of said opening for driving said member; a plurality of drill points extending forwardly from said housing, said drill points being longer than said cutting means to enter a workpiece ahead of said cutting means whereby said device is stabilized against movement in the plane of the workpiece; said housing including an aperture located in the center thereof to enable an operator to sight on the center of a desired hole location.
 2. A cutter accessory adapted to be used with a portable drill for cutting rectangular holes in sheet material comprising a housing; an endless chain mounted for movement within said housing; a plurality of cutting blades carried by said chain and extending forwardly of said housing; drive means for driving said chain within said housing, said drive means including first and second independent drive means offset from the center of said rectangles, each of said first and second drive means including a drill point extending forwardly of said housing, said drill points extending further from said housing than said blades to define the location of said cutter prior to engagement of said blades with the work whereby rotational instability is reduced; a plurality of idlers juxtaposed with said drive means to lead said chain around the corners of a desired rectangular shape; and said housing including an aperture extending therethrough fOr sighting on the center of a location to be cut. 